Its a Garrett/Air research M10, exactly like is says. M10/11 are casting numbers. It's a T3 (variant) i believe. there are several variations of that turbo. for starters, what is it from? they are very common on early 90's Saab's (9000t for example) with A/R .48 and .49 exhaust. Could be completely different though, looks bigger then a saab version